The therapeutic community (TC) is one of the major treatment modalities that has accommodated the recent surge in adolescent admissions to residential treatment programs. Although this modality has proven effective for adolescents, there is limited understanding of how TC treatment produces outcomes. Quality of care improvements within adolescent TC programs are best informed by direct assessment of the treatment process;yet few measures of treatment process exist, especially for use with adolescents in TC treatment. In light of the distinct needs of adolescents in substance abuse treatment, the emphasis on decoupling adult and adolescent treatment services, and the recognition that adolescent substance abuse treatment should ideally be tailored to address adolescents'particular issues, it is increasingly important to have reliable and valid measures of treatment process that are specific to this growing population of substance abuse treatment consumers. The proposed study will seek to improve measurement of adolescent TC treatment process through completion of the following specific aims: 1) To refine two measures of adolescent TC treatment process, the self-report Dimensions of Change Instrument (DCI-A) and counselor-report Counselor Assessment of Treatment Engagement (CATE), through the use of consensus panels, focus groups, cognitive interviewing, and small-scale piloting;and 2) To examine the psychometric properties and gather preliminary validity evidence for these two refined measures using data from a cross-sectional pilot study involving 280 adolescent clients and 60 counselors at 7 TC treatment program sites across the nation.